The ancient civilization known for its elaborate temple complexes and intricate mythology is the Mesopotamian civilization, particularly the Sumerians. This civilization, which developed in the fertile plains between the Tigris and Euphrates rivers, is renowned for its advancements in writing, agriculture, and urbanization. They constructed massive ziggurats, serving both religious and administrative purposes, and their mythology reflected complex beliefs in gods and creation stories. The Sumerians' contributions, including the invention of cuneiform writing and a calendar, laid foundational elements for future civilizations in the region.